Speech recognition systems are well known technologies today. A speech recognition system is used, for example, in telephone automated response systems, communication system and other systems in which it is desirable to be able to have a computer system recognize speech and commands from a human being and then act on those commands. An example of a commercially sold speech recognition system is sold by Nuance Communications, Inc.
One problem that exists in speech recognition systems is scalability. In particular, when a speech recognition system is scaled in size, the number of user names in the speech recognition database becomes very large. As a result, it becomes more difficult for the speech recognition system to correctly recognize a user name. As a result, the user experience with the speech recognition system can be frustrating or the speech recognition system can fail to corrected identify a user based on a voice command.
In some applications of speech recognition that require calling, the frequency of calls made by a given person to other persons is non-uniform; i.e., some users are called by a given user with greater probability than others. In certain contexts, the patterns of calling may satisfy the following two properties.                The locality property of a speech recognition system, which means that a person in a particular group (or department) tends to call people in a limited set of other groups (or departments).        The substitutability property of a speech recognition system, which means that a person in a particular group tends to call the same other groups as other people who are in the same particular group.        
These properties can be harnessed to overcome the scalability problem with speech recognition system and it is desirable to provide a speech recognition system and method that harnesses these properties and it is to this end that the disclosure is directed.